1. Field of the Invention
The present invention relates to a construction for attaching a radiant heat blocking metal foil, serving as an insulating means, to an insulated container, in order to maintain and improve the insulating properties of insulated containers, including household insulated containers such as vacuum flasks, cooler boxes and heat-retaining lunch boxes, and insulating materials used for thermal insulation equipment.
This application is based on Patent Application No. Hei 9-270186 filed in Japan, the content of which is incorporated herein by reference.
2. Description of the Related Art
With household insulated containers such as vacuum flasks, particularly metal vacuum flasks, cooler boxes and heat-retaining lunch boxes, and thermal insulation equipment such as refrigerators, as an insulating means for retaining heat, there are those which use vacuum insulation or a solid insulating material such as urethane foam, and those which use an insulating layer with a gas having low thermal conductivity such as krypton, xenon or argon, or air filled between the container walls. Moreover with any of these, in order to improve the insulating property for retaining heat, a plating layer may be formed on the container wall where the insulating layer is formed, using a metal having high thermal reflectivity such as aluminum, copper, nickel and the like, or these metals may be made into a foil which is disposed on the face of the container wall of the insulating layer, to thereby reduce heat loss due to the radiant heat which is one of the factors in insulation.
With the above method where a plating layer is formed however, there is the disadvantage in that the plating operation is not only complex but also manufacturing costs are high. Accordingly, the method where a metal foil is disposed on the face of the container wall of the insulating layer is widely used, because it has the advantage that the manufacturing process is simpler and manufacturing costs are less. With this method however, when the foil is secured to the container wall face of the insulating layer, it is secured by positioning double-sided adhesive tape or an adhesive on the back face of the metal foil. At the time of attaching the foil, since the adhesive tape or the adhesive is hidden on the back of the foil and cannot be seen by the worker fitting the foil, it is difficult to check the state of the adhesive tape and the positional relation between the adhesive tape and the container wall face where it is attached. Therefore, it is necessary to make a preliminary plan in detail for the arrangement and carry out a rehearsal operation. Moreover, once the foil is attached, if the proposed attaching position is not correct, it is very difficult to peel off and re-adhere without damaging the thin and easily damaged foil.
When the metal foil is disposed on the container wall face of the insulating layer, if the container wall face on which this is to be arranged is for example parallel flat surfaces or a cylindrical side wall face, there will be no problem. However, if the metal foil is to be disposed on a container wall face which is not uniform parallel faces, such as a sphere or a conical face, the metal foil will have remaining faces. Therefore, complicated manufacturing process and design control have been necessary to uniformly adhere the metal foil, by overlapping or cutting out the remaining faces. Furthermore, in spite of the detailed design control and manufacturing process, it is very difficult to adhere and secure the metal foil to container wall faces which are not uniform, in a state where it is disposed uniformly as desired.